000 AXNT20 KNHC 182358 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 758 PM EDT Sun Jun 18 2017 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2345 UTC. ...SPECIAL FEATURES... Potential Tropical Cyclone Two has developed, as of 2100 UTC. Its center is located near 7.5N/50.4W, moving west at 20 kt. Maximum winds are 30 kt with gusts up to 40 kt. This system is expected to continue moving west across the southeast Caribbean while intensifying through the next 48 hours, then weakening by Wednesday. Please see latest full NHC Potential Tropical Cyclone Forecast/Advisory and Intermediate Public Forecast/Advisory under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC and MIATCPAT2/WTNT32 KNHC for more details. A broad area of low pressure in the northwestern Caribbean Sea is centered by a 1006 mb low near 19N87W. This system is generating clusters of heavy showers with embedded thunderstorms north of 12N and west of 78W affecting western Cuba, western Jamaica, Cayman Islands, the Yucatan Peninsula and Central America. Gale-force southeast winds are N of 19N between 81W and 83W with seas of 9 to 11 ft. Fresh to near-gale force winds are elsewhere north of 16N between 78W and 84W with seas to 10 ft. These conditions are forecast to continue through Monday morning. Gradual development of this system is expected while it moves slowly northwestward across the Yucatan Peninsula later today and over the southern or central Gulf of Mexico on Monday and Tuesday, where a tropical or subtropical cyclone is likely to form. Regardless of development, heavy rains are expected over portions of Central America, the Yucatan Peninsula, Jamaica, the Cayman Islands, and western Cuba during the next several days. The chance of formation into a tropical cyclone during the next two days is high. Please read the latest NHC Tropical Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the east Atlantic associated with a 1010 mb low near 08N25W. Its axis extends from 13N25W to the low to 02N26W, moving west at 20 kt. CIRA LPW imagery shows a moderate moist environment within this wave with some patches of dryness associated with Saharan air and dust intrusion. Upper-level divergence supports isolated showers within 50 nm around the low center. A tropical wave is in the central Atlantic with axis extending from 11N35W to 03N36W, moving west at 10-15 kt within the last 24 hours. Extensive intrusion of Saharan dry air and dust is observed in this wave's environment which is limiting the convection to isolated showers within 120 nm either side of the axis from 05N to 08N. The tropical wave and low along 49W is now the Potential Tropical Cyclone Two. This system is described in the Special Features Section above. A tropical wave is located within 100 nm east of the Lesser Antilles. Its axis extends from 19N58W to 09N59W, moving west at 15-20 kt within the last 24 hours. Shallow moisture and a mid- level divergent environment ahead of the wave support scattered showers and thunderstorms south of 18N between 59W and 64W. ...MONSOON TROUGH/ITCZ... The Monsoon Trough extends from the coast of west Africa near 14N17W to a 1010 mb low near 09N25W to 06N31W. The ITCZ extends from 04N36W to 05N43W, then resumes W of a tropical wave near 05N52W to 06N58W. Three tropical waves are embedded within the Monsoon trough/ITCZ. See tropical waves and special features sections for information about convection. ...DISCUSSION... GULF OF MEXICO... Broad surface high press covering great portions of the Atlantic waters extends its ridge axis across the Florida peninsula and the northern Gulf waters. With this, a gentle to moderate southeast flow extends across the basin, except for the southeast Gulf. In this area, the Special Feature low centered over the northwest Caribbean supports moderate to fresh easterly winds. Please refer to the section above for more details about the low. Scattered showers associated with the rainbands of this systems are already affecting the Florida straits and the Yucatan channel. CARIBBEAN SEA... The major concern in the basin is a broad area of low pressure located over the northwest Caribbean, which is generating numerous heavy showers and strong to gale-force winds. Gradual development of this system is expected while it moves slowly northwestward across the Yucatan Peninsula later today and over the southern or central Gulf of Mexico on Monday and Tuesday, where a tropical or subtropical cyclone is likely to form. See the Special Features section for more details. Scattered showers and thunderstorms are prevailing over the far east Caribbean ahead of a tropical wave that extends along 59W. See the Tropical Waves section for further details. A surface trough off the coast of Panama is supporting scattered showers and thunderstorms south of 14N between 75W and 79W. ...HISPANIOLA... Isolated showers are across the island being influenced by the broad area of low pressure in the NW Caribbean. Showers are forecast to continue through the evening hours. ATLANTIC OCEAN... Three tropical waves and a potential tropical cyclone are moving westward between the coast of Africa and the Lesser Antilles. Please refer to the sections above for details. A diffluent flow aloft combined with the broad low centered over the northwest Caribbean are enhancing isolated showers across the Florida Straits and the Bahamas mainly west of 77W. Otherwise, a broad high pressure covers the Atlantic from the Azores to the Florida Peninsula, with a 1024 mb high pressure near 29N48W. For additional information please visit http://www.hurricanes.gov/marine $$ ERA